Just wondering... I've seen mechanical "bypasses" on old muscle cars to bypass the cat... I was wondering if we would gain anything from this?
-- Aaron

 

Isn't there an 02 sensor in the cat that makes the engine run properly?

 

[QUOTE]Originally posted by amartin
[B]Just wondering... I've seen mechanical "bypasses" on old muscle cars to bypass the cat... I was wondering if we would gain anything from this?

 

You may even lose torque because of reduced back pressure.

 

I don't know about bypassing cat but if you are going catless I can tell you of few things cause I've done it out of curiousity. With Mugen ECU I was able to run with BYS straight pipe without inducing check engine light and anomalies such as extra noise.
Torque didn't change but the gain was there but very small to insignificance.

But the problem was that it would guzzle gas like crazy even driving mildly.
With the type of driving I do, I would literally fill up every two days, not a good thing.
So I took it off when I sold the ECU

I still have the shiny good looking Back Yard Special Staight Pipe in my basement, if anyone wants it give me an offer.

 

I thought I would get additional gains from my SC without the catalyst (+ Mugen ECU)... but it seems that I didn't. I'm getting a bit less HP at the wheels than SCS2K who is completely stock + SC...

I'm going to eventually put the catalyst back in and put less pollutants into the air...

 

Interesting to know... thanks so much for theinfo.
-- Aaron

 

Removing the cat makes a HUGE difference on many turbo cars (40-60 hp on a MKIV Supra, for example) and also helped my friend's C5 Vette. However, it will trigger the "check engine" light b/c of the O2 sensor not obtaining a reading. You can wire a fix by simulating a normal O2 signal to the sensor, but I'm not sure if it's worth it on a NA car.